Behind-the-scenes on the set of 'Upside Down'

For the Floor Zero scenes, McDowell’s team built two sets (above), which sat side-by-side, as if the screen had been sliced down the middle and folded open. When characters between the two worlds interact, the “down” scene takes place on one set and the “up” scenes takes place on the other, simultaneously.

Courtesy of Alex McDowell

These shots are spliced together in post-production, allowing for “Up Top” and “Down Below” to exist on the screen simultaneously.

Courtesy of Millennium Entertainment

Dunst and Sturgess prep for a scene using wire work. Dunst was already a pro from her “Spider-Man” days, but Sturgess had to arrive on set a month early to learn the ropes.

“It’s really unnatural,” says Sturgess, “If you don’t move with the flow of the wire, you sort of jolt in mid-air. [The key is] feeling comfortable and looking seamless like the wires are not there.”

Sturgess shoots a scene on the mountain top set.

Courtesy of Alex McDowell

Sturgess and Dunst share a romantic, but potentially uncomfortable kiss thanks to the rules of opposite gravity in this universe.

Courtesy of Millennium Entertainment

“We built one classic, MGM 1930s set with a giant rotating room,” says McDowell. “So there is a camera locked to a massive wheel that has a set inside it. The camera and the wheel are moving together, which is the way a lot of ‘Inception’ was shot, on a much larger scale.”

Courtesy of Alex McDowell

Solanas directs Sturgess and Dusnt in a scene.

One set featured an upside chandelier. “We built three quarters of a chandelier, not the very top, but everything else, [and there] was a steel rod up the center holding it down,” says McDowell. “We had to wire up the crystals so that they looked like they were hanging.”

Courtesy of Alex McDowell

Dunst and Sturgess film a scene. While the director and production designer wanted to use real-life environments as much as possible, green screen was necessary to expand beyond the set in places such as windows.